In general terms, an oil well pumping system begins with an above-ground pumping unit, which creates the up and down pumping action that moves the oil (or other substance being pumped) out of the ground and into a flow line, from which the oil is taken to a storage tank or other such structure.
Below ground, a shaft is lined with piping known as “tubing.” A sucker rod, which is ultimately, indirectly coupled at its north end to the pumping unit is inserted into the tubing. The sucker rod is coupled at its south end indirectly to the oil pump itself, which is also located within the tubing, which is sealed at its base to the tubing. The sucker rod couples to the oil pump at a coupling known as a 3-wing cage.
Beginning at the south end, oil pumps generally include a standing valve, which has a ball therein, the purpose of which is to regulate the passage of oil (or other substance being pumped) from downhole into the pump, allowing the pumped matter to be moved northward out of the system and into the flow line, while preventing the pumped matter from dropping back southward into the hole. Oil is permitted to pass through the standing valve and into the pump by the movement of the ball off of its seat, and oil is prevented from dropping back into the hole by the seating of the ball.
North of the standing valve, coupled to the sucker rod, is a traveling valve. The purpose of a conventional traveling valve is to regulate the passage of oil from within the pump northward in the direction of the flow line, while preventing the pumped oil from slipping back down in the direction of the standing valve and hole.
In use, oil is pumped from a hole through a series of “downstrokes” and “upstrokes” of the oil pump, wherein these motions are imparted by the above-ground pumping unit. During the upstroke, formation pressure causes the ball in the standing valve to move upward, allowing the oil to pass through the standing valve and into the barrel of the oil pump. This oil will be held in place between the standing valve and the traveling valve. In the conventional traveling valve, the ball is located in the seated position. It is held there by the pressure from the oil that has been previously pumped. The oil located above the traveling valve is moved northward in the direction of the 3-wing cage at the end of the oil pump.
During the downstroke, the ball in the conventional traveling valve unseats, permitting the oil that has passed through the standing valve to pass therethrough. Also during the downstroke, the ball in the standing valve seats, preventing the pumped oil from slipping back down into the hole.
The process repeats itself again and again, with oil essentially being moved in stages from the hole, to above the standing valve and in the oil pump, to above the travelling valve and out of the oil pump. As the oil pump fills, the oil passes through the 3-wing cage and into the tubing. As the tubing is filled, the oil passes into the flow line, from which the oil is taken to a storage tank or other such structure.
In a tubing pump, the barrel assembly is coupled to and becomes a part of the well tubing. Alternatively, with an insert pump, the complete pump is attached to the sucker rod string and is inserted into the well tubing with the sucker rod string. As a complete unit, an insert pump may be inserted and pulled out of the well without removing the well tubing.
Beginning from the south end and heading northward, an insert pump may comprise a mandrel, a standing valve, a traveling valve, a top plunger adapter, and a valve rod guide. When a conventional insert pump is inserted into the well tubing, the valve rod is typically fully extended out of the insert pump so that the traveling valve is positioned at the north end of the insert pump and away from the standing valve which is positioned at the south end of the insert pump. This causes the pump to become full of air that is trapped within the space between the traveling valve and the standing valve. When the insert pump is lowered into the well, the fluid may compress the air and the fluid may overtake the top of the insert pump and capture the air within the pump, causing gas lock.
The present invention addresses this problem encountered in the prior art pumping systems, by proving a latch system. The latch system allows the traveling valve to be fixed at the southern position of the insert pump while the insert pump is lowered into the well tubing. By having the traveling valve at the southern position, air is not allowed to collect between the traveling valve and the standing valve. As the insert pump is lowered into the well, the insert pump acts like a straw and allows the pump to be filled with fluid, not with air, thus preventing gas lock.